Display screen or portion thereof with a graphical user interface



The FIGURE is a front view of a display screen or portion thereof with a graphical user interface.

The ornamental design which is claimed is shown in solid lines in the drawings. The broken line showing of a display screen with the graphical user interface is included for the purpose of the showing portions of the article which form no part of the claim. Broken lines formed by equal length dashes show unclaimed portions of the design. 

CLAIM The ornamental design for a display screen or portion thereof with a graphical user interface, as shown and described. 